IS 875 Part 3 Wind Load Calculator
A professional BIS-compliant utility to compute design wind pressure (Pz) and static uplift forces for commercial rooftop and ground-mounted solar structural arrays in India.
1 Calculation Parameters
2 Live Engineering Output
✓ High Integrity Required
At this wind velocity, standard sheet clamping is vulnerable. Hot-dip galvanized structural profiles complying with IS 2629 / IS 4759 standards and dual-clamping systems are highly recommended to prevent panel pull-out.
Understanding IS 875 Part 3 Calculations
The calculations executed by this tool strictly mirror the formulas laid out by the **Bureau of Indian Standards (BIS)** inside the building design code **IS 875 (Part 3): 2015**. To guarantee structure safety, solar racks must be engineered to resist extreme local winds.
1. The Design Wind Speed (Vz)
Wind speed varies by terrain roughness, altitude, and local topography. The standard basic wind speed (Vb) is adjusted using multipliers:
- k1 (Risk Factor): Accounts for the probable design life of the grid structure. Standard values are 1.0 for 50-year structures and 0.92 for 25-year systems.
- k2 (Terrain & Height): Reflects the structural elevation. As height increases, wind speed scales upwards.
- k3 (Topography): Scales forces upwards if structures reside on hills or ridges exceeding 3°.
- k4 (Cyclonic Zone): A mandatory multiplier of 1.15 for coastal towns in cyclonic belts (within 60km of the eastern coast).
2. The Design Wind Pressure (Pz)
Design wind pressure converts wind velocity directly into active mechanical forces. The relationship is quadratic, meaning small wind speed increases cause disproportionately higher lift profiles:
Uplift Force Control: Wind hitting modules tilted upwards creates strong aerodynamic lift forces. To maintain structural stability, the anchoring fasteners (chemical anchors or mechanical expansion bolts) must resist this calculated uplift value multiplied by a structural safety coefficient of at least 1.5x.
Link & Cite This Engineering Utility
Using this calculator in your structural designs, project proposals, or website content? Citing this tool verifies design assumptions for site inspectors, EPC audits, and clients.